How to substitute yarn in a knitting or crochet pattern

The yarn a pattern calls for may be discontinued, too expensive, not sold where you live, or simply not your favorite. You can almost always use another one. Here's how to choose it so your project still comes out the right size and feels the way it should.

1. Match the gauge first

Gauge is the number of stitches and rows in 10 cm (4 in), and it's the single most important thing to match. A sweater knit at 20 stitches instead of 22 per 10 cm ends up about 10 % wider. Look for a yarn whose recommended gauge on the label is the same as, or very close to, the pattern's.

The yarn weight category (fingering, DK, worsted …) is a good starting point, but the categories are broad. Meters per 100 g tells you more about how thick a yarn really is:

These are typical ranges, not rules: fiber and how a yarn is spun change the numbers. Two yarns with a similar meters-per-100 g and the same recommended gauge are usually a safe swap.

2. Compare the fiber

Yarns of the same thickness can behave very differently. Think about what the original fiber does in the finished piece:

• Wool is elastic and springs back, which is why ribbing and fitted garments love it.
• Cotton and linen are heavier, cooler and have little stretch, so they hang and can grow in length.
• Alpaca and silk drape beautifully but are less springy; alpaca also adds warmth and a soft halo.
• Superwash wool tends to relax and grow a little more after washing than untreated wool.
• Acrylic and blends are easy-care and often elastic; good blends behave close to wool.

Swapping within the same fiber family is easiest. If you change fiber, choose one with similar elasticity for fitted pieces, and expect more drape (and sometimes a heavier fabric) when you move toward cotton, linen, silk or alpaca. Looking for a vegan alternative to wool? Cotton, linen, bamboo-based yarns and good acrylic blends are worth a swatch.

3. Work out how much yarn you need

Never go by the number of skeins, always by length, because skeins of different yarns hold different amounts.

1. Multiply the skeins the pattern asks for by the length of one skein of the original yarn.
2. Divide that total by the length of one skein of your new yarn.
3. Round up, and add one skein as a buffer, especially if you change the length or the size.

Example: the pattern asks for 8 skeins of a yarn with 125 m each, so 8 × 125 = 1000 m. Your new yarn has 100 m per skein: 1000 ÷ 100 = 10 skeins, plus one for safety, so buy 11. Buy them from the same dye lot so the color matches.

4. Swatch, wash, measure

Knit or crochet a swatch of at least 12 × 12 cm in the pattern's stitch, then wash and dry it the way you'll treat the finished piece. Measure in the middle, away from the edges. Too many stitches per 10 cm? Go up a needle or hook size. Too few? Go down. It takes an hour and saves you from a sweater that doesn't fit.

Let YarnSpace do the comparing

YarnSpace's Yarn Alternatives looks at the yarn a pattern calls for and ranks substitutes by gauge, meters per 100 g and fiber, with vegan options if you like. It works out how many skeins of the new yarn you need, shows prices from yarn shops in your country, and lets you compare two yarns side by side. It also checks your stash first, in case the right yarn is already at home.

Find a yarn that knits up the same

YarnSpace is the knitting and crochet app for iPhone, iPad, Mac and Apple Watch.

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